The subject matter of the invention is an emission electron microscope for the imaging of the surfaces and the angle distribution of the electrons emitted from the surface.
The system of the electrostatic lenses, known from U.S. Pat. No. 4,096,386, is characterized in that one of the lenses, e.g. the first, has a polished, flat electrode that deflects the light into the direction of the surface.
Also known from German patent application DE 198 9003 is an electron optical, imaging photo electron microscope that contains an electrostatic lens system and an image converter, the attribute of which is the suppression or retardation of the electrons.
An instrument and method of calibrating the same for the object imaging are known from U.S. Pat. No. 6,011,262, which is characterized in that the instrument contains a number of apertured diaphragms for the selective generation of the electron optical images. The instrument is also equipped with a Wien filter that enables the illumination with an electron beam.
The emission electron microscope, which comprises an objective lens having a contrast diaphragm system, a stigmator, and an electron optical imaging system having at least one lens, is additionally provided with a second, independent imaging system that is parallel to the first imaging system, and two electron detectors for the independent receipt of two images: the real image and the image of the angle distribution of the electrons, which is possible by the electronic switching of the potentials of the two deflection elements, which deflect the electron beam about an angle xcex2 and xe2x88x92xcex2, and are electron optically separated from one another by double their focal length, whereby each deflection element is comprised of two spherical and concentric electrodes, of which the outermost one has a bore in order to enable the drift of the electrons along the electron optical axis with the deflection being switched off.
The emission electron microscope is also provided with: a localized electron source that is disposed closely adjacent to the electron optical axis of the objective lens and emits the electrons at an angle xcex1 to the axis of the objective lens, a contrast diaphragm system in one of the planes that is conjugated to the focal plane of the objective lens, and an image diaphragm system in one of the image planes of the emission electron microscope.
The emission electron microscope is provided in an electron suppressing or retarding system that comprises at least one electrode that simulates a spherical, suppressing central field having a center in the focal point of the objective lens.
The electron source can also become the source for the spin-polarized electrons. In the further embodiment of the emission electron microscope, the deflection system is provided with an electron detector that is disposed after the bore in the outer deflection electrode of the second deflection element and serves for the receipt of the energy spectrum.
In the further variant of the emission electron microscope, which comprises: objective lens, contrast diaphragm system, stigamator, and an imaging system having at least one lens, the emission electron microscope is provided not only with a localized electron source that is disposed closely adjacent to the electron optical axis of the objective lens, and that emits the electrons at the angle xcex1 to the axis of the objective lens, as well as a contrast diaphragm system in one of the planes conjugated to the focal plane of the objective lens, and an image diaphragm system in one of the image planes of the system.
The electron suppression or retardation system comprises at least one electrode that simulates a spherical and suppressing central field with the center in the focal point of the objective lens, and in one of the planes correlated to the focal plane of the objective lens there is disposed a contrast diaphragm system.
In the further embodiment, the electron source or the source of the spin-polarized electrons is provided with a deflection.
Coupled with the objective lens of the emission electron microscope, in a mechanical manner, is a piezoquartz driven specimen manipulator that enables the shifting, cooling and heating of the specimen.
An advantageous result of the invention is provided by: the characteristic of the imaging of the specimen surface with electrons from the selected energy range, the possibility of the local measurements of the energy spectrum and the angle distribution of the electrons, the possibility of the simultaneous receipt of the real image and an image of the angle distribution of the electrons correlated thereto. The production of this effect is realized by the use of an electronic optical deflection system that displaces the electron beam in a parallel manner, and the insertion of the electron gun into the system.